Overcoming Wellbore Cleanup Challenges in Deepwater Wells in West Africa

Abstract

Mesophase technology for wellbore cleanup and remediation in the drilling industry has been used in various oil fields to increase well productivity and injectivity. The majority of these applications include oil-based mud filter cake removal, nearwellbore remediation, and wellbore displacement. The openhole wells completed with standalone screens in deepwater tertiary formations offshore West Africa have benefited from previous knowledge and experiences accumulated by the operator and the service company in the application of mesophase technology in other fields. This paper discusses the field application of mesophase technology in several deepwater offshore fields in West Africa. Prior to the field application, the mesophase formulation was customized for the field conditions, such as temperature, fluid density, type of completion brine, and the specific oil-based mud. The customized formulation was evaluated to determine the regain of injection permeability, fluid compatibility, and the breakthrough time. Intensive tests were required to fine-tune the formulation to obtain the desired high injection permeability for the challenging field conditions. Results from the laboratory and description of the field application are discussed and presented in this paper. The field applications data proved that, after placement of the mesophase treatment in the wells, diffusion of the treatment produced: (1) break-up of blocking solids from the completion screens; (2) removal of filter-cake residues; and (3) water-wetting of all solid surfaces. This cleaning treatment gave very good results in the production and water-injection wells.

Development of wellbore compound blockage removal technology to reduce production loss in the ultra-deep and high-sulfur Yuanba gas field

“…The injection of hot oil or hot water is used as the thermal treatment (Zhang et al 2020;Creek 2012;Ding et al 2017). The chemical treatment primarily refers to the injection of acid and other chemical solvents (Davudov et al 2018;Pietrangeli et al 2014). Therefore, in the early stage the injection of hot water and inorganic acid is used to remove the wellbore compound blockages for most blockage wells of Yuanba gas field.…”

One-Stage Calcium Carbonate Oil-Based Filter Cake Removal Using a New Biodegradable Acid System

“…They concluded that microemulsion fluids were able to effectively remove synthetic and oil-based filter cake and the near-wellbore damage. For successful operations, the microstructure of microemulsion should be characterized to customize the microemulsions for a certain application [29,30].…”